High-processability high-density ethylene-based polymer using hybrid supported metallocene catalyst, and preparation method therefor

ABSTRACT

The present invention relates to a high-density ethylene-based polymer comprising an ethylene homopolymer or a copolymer of ethylene and at least one comonomer selected from the group consisting of an α-olefin, a cyclic olefin, and a straight, branched and cyclic diene. According to the present invention, the high-density polyethylene resin has a wide molecular weight distribution and excellent comonomer distribution characteristics, has excellent melt flowability due to a long chain branched structure, and has excellent mechanical characteristics since the comonomer distribution is concentrated in a high-molecular-weight body. The high-density ethylene polymer of the present invention has excellent molding processability during processing such as extrusion, compression, injection and rotational molding by having excellent mechanical characteristics and melt flowability.

TECHNICAL FIELD

The present invention relates to a high-density ethylene-based polymerusing a hybrid supported metallocene catalyst and a preparation methodthereof, and more particularly, to a high-density polyethylene polymerwhich satisfies the balance of excellent mechanical properties andexcellent molding processability, as compared with a conventionalhigh-density ethylene-based polymer. The present invention relates tothe high-density polyethylene polymer which has excellent mechanicalproperties since the high-density ethylene-based polymer has excellentprocessability due to a wide molecular weight distribution and a longchain branch and has a high molecular weight.

BACKGROUND ART

The mechanical and thermal characteristics of polyethylene resins areaffected by molecular weight and density, and the application fields arechanged accordingly. Generally, as the density of the polyethylenepolymer is lower, the transparency and impact strength thereof becomebetter, but the polyethylene polymer has a disadvantage that physicalproperties such as heat resistance, hardness, and flexural modulus aredeteriorated and the chemical resistance is also deteriorated.

On the other hand, as the density of the polyethylene polymer is higher,the physical properties such as heat resistance, hardness, and flexuralmodulus become better, and the chemical resistance increases, but thetransparency and impact strength thereof are deteriorated. Therefore,when producing injection products using an ethylene copolymer,especially various industrial products such as cartridges and pailcontainers, it is very difficult to produce injection products havingexcellent impact strength and excellent chemical resistance. Inparticular, since injection products such as various industrial productsrequired in the market require high impact resistance, the necessity ofsuch technology is very high.

High-density polyethylene polymers are available for many applicationsthrough various molding methods. For example, as a typical method for afilm molded product, there is an inflation method in which a moltenpolymer extrudate is inflated by melting a high-density polyethylenepolymer and extruding a high-density polyethylene polymer from a moldwhile blowing air thereinto. In addition, as a method for obtaining amolded product having a desired shape, there is a blow molding method inwhich a molten high-density polyethylene polymer is blown into a cavityof a die and air is blown into a molten resin in the cavity of the dieso as to expand and press the molten resin on a cavity inner wall tothereby form a molten polymer in the cavity. There is also an injectionmolding method in which a molten high-density polyethylene polymer ispressed in a cavity of a die so as to fill the cavity.

As described above, the high-density polyethylene polymer may beprepared by various molding methods, but these methods are common inthat the high-density polyethylene polymer is first heated to a moltenstate and then molded. Therefore, the behavior of the high-densitypolyethylene polymer at the time of heating and melting, that is, themelting property, is an extremely important physical property in themolding of the high-density polyethylene polymer.

In particular, in the molding such as extrusion molding, compressionmolding, injection molding, or rotational molding, the melting property,especially the melt flowability of the high-density polyethylene-basedpolymer, is an essential property that affects satisfactory moldability.The molding processability used herein is not limited to theprocessability at the time of extrusion molding, compression molding,injection molding, or rotational molding.

Generally, it can be said that melt flowability is more excellent as anMI, an MFI, or an MFR is larger. Practically, however, since propertiesrequired for polymers as molding materials are different for eachmolding method, the index used as the standard indicating moldingprocessability is changed according to the molding method. For example,in the injection molding method, a high-density polyethylene polymerhaving a narrow molecular weight distribution tends to be used so as toobtain a molded product having impact resistance.

The high-density polyethylene polymer conventionally used for extrusionmolding, compression molding, injection molding, or rotational moldingis generally prepared by using a titanium-based Ziegler-Natta catalystor a chromium-based catalyst.

The high-density polyethylene polymer prepared by using such a catalystcan improve melt flowability due to a wide molecular weightdistribution, but has a drawback in which mechanical properties such asimpact resistance are significantly deteriorated due to mixing oflow-molecular-weight components, and chemical resistance is deterioratedsince a comonomer is intensively distributed in a low-molecular-weightbody. Therefore, there has been a problem that it is impossible toincrease a speed in injection molding while maintaining excellentmechanical properties.

To solve these problems, many studies on metallocene catalysts have beenconducted. U.S. Pat. No. 6,525,150 discloses a metallocene catalystcapable of producing a resin having a narrow molecular weightdistribution, and in the case of a copolymer, a uniform comonomerdistribution by using uniform active sites of metallocene. However,since the molecular weight distribution is narrow, the mechanicalstrength is excellent, but the molding processability is low.

As described above, in the case of a single metallocene catalyst, sincea molecular weight distribution is narrow due to uniform active sites,molding processability is not satisfactory. Therefore, the applicationdevelopment of metallocene catalyst systems has not been much conductedin the field of high-density polyethylene polymers in which the balancebetween mechanical properties and moldability is important.

In order to solve these problems, many proposals have been made to widena molecular weight distribution by using a plurality of reactors or bymixing many kinds of metallocene catalysts.

However, when the method for widening the molecular weight distributionis used, moldability is improved, but other physical properties areinevitably deteriorated. Thus, it is impossible to obtain a high-densitypolyethylene polymer having excellent physical properties, such asmechanical strength, which can be obtained by narrowing the molecularweight distribution.

In addition, a method for improving a melt tension by maintaining anintrinsic viscosity of a catalyst has been proposed, but this methodcannot improve the deterioration of melt flowability and thus high-speedmolding is difficult.

In order to solve the problem of the metallocene catalyst, the meltflowability of the polymer is improved by using a catalyst in which along chain branch (LCB) is introduced into a main chain of the polymeras a side branch, but there is a problem that mechanical properties suchas impact resistance are significantly lower than those of the case ofusing a general metallocene catalyst.

In addition, as another method, a method for preparing polyolefin havinga bimodal molecular weight distribution by using catalysts havingdifferent reactivity to a comonomer is proposed. However, the polyolefinhaving the bimodal molecular weight distribution, which is prepared inthe above-described manner, has improved melt flowability, but hasdifferent molecular weight distributions and thus low kneadingproperties. Therefore, there is a problem that it is difficult to obtaina product having uniform physical properties after processing, andmechanical strength is deteriorated.

Many methods have been proposed so as to improve the mechanicalproperties and melt flowability of high-density polyethylene polymersprepared using metallocene catalysts, but most methods propose only thesolution to linear low-density polyolefins. In addition, sincemetallocene has characteristics that the activity tends to decrease asthe concentration of the comonomer decreases, the activity in thepreparation of the high-density polyolefin is low and thus it is notcost-effective.

Even in the case of the catalyst having excellent activity andprocessability in preparation of the low-density polyolefin, theactivity in the preparation of the high-density polyolefin is low andthus it is not cost-effective. In particular, in a gas phase process, alot of fine particles are formed and stable work is difficult.

In a gas phase reactor, activity is an important factor. Due to the lowactivity, a large amount of fine particles are formed, causing a largeamount of static electricity. The static electricity is attached to thewall surface of the reactor to obstruct a heat transfer and lower apolymerization temperature. In addition, since the fine particlesattached to the wall surface of the reactor continue to grow, theproduction is stopped.

A catalyst for solving the above-described problems and preparing ahigh-density polyolefin polymer having excellent mechanical strength,excellent melt flowability, and high activity is continuously required,and the improvement thereof is required.

DESCRIPTION OF EMBODIMENTS Technical Problem

The present invention has been made in an effort to solve theabove-described problems.

The present invention provides a high-density ethylene-based polymer,which simultaneously satisfies mechanical properties, chemicalresistance, and excellent molding processability that a conventionalhigh-density ethylene-based polymer has not exhibited, and a preparationmethod therefor.

Another object of the present invention is to provide a high-densityethylene-based polymer, which has a high characteristic relaxation time(λ) and excellent processability, and a preparation method therefor.

Another object of the present invention is to provide a high-densitypolyethylene polymer, which has a unimodal molecular weight distributionthat is excellent in impact strength, flexural strength, environmentalstress cracking resistance (ESCR), and melt tension since a content of acomonomer is high in a high-molecular-weight body prepared in thepresence of a hybrid supported metallocene catalyst described below andthe content of the comonomer is low in a low-molecular-weight body, anda preparation method therefor.

Another object of the present invention is to provide a high-densitypolyethylene polymer, which has a wide molecular weight distribution anda long chain branched structure and thus has excellent productivity dueto a small load during processing such as extrusion molding, compressionmolding, injection molding, or rotational molding, and a preparationmethod therefor.

Solution to Problem

In order to achieve the above-described objects of the present inventionand achieve the characteristic effects of the present inventiondescribed below, the characteristic construction of the presentinvention is as follows.

According to the present invention, a density is 0.930 g/cm³ to 0.970g/cm³, an MI is 0.1 g/10 min to 50 g/10 min at 190° C., an MFR is 35 to100, a characteristic relaxation time (λ) is 0.3 s to 2.0 s at 190° C.,and a relationship between the MI and the characteristic relaxation time(λ) satisfies the following Equation:

−0.445 ln(MI)+3.6023>λ,>−0.323 ln(MI)+0.696.

Advantageous Effects of Disclosure

A high-density ethylene-based polymer, which is prepared under existenceof a hybrid supported metallocene catalyst, has excellent meltflowability and has excellent characteristics in impact strength,flexural strength, environmental stress cracking resistance, and melttension.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph showing a relationship of an MI and a characteristicrelaxation time (λ) according to Example and Comparative Example.

FIG. 2 is a complex viscosity graph of Examples 2 to 4 and ComparativeExample 2 and 3.

FIG. 3 is a complex viscosity graph of Example 5 and ComparativeExamples 4 to 7.

FIG. 4 is a complex viscosity graph of Examples 6 and 7 and ComparativeExample 9 to 12.

FIG. 5 is a van Gurp-Palmen graph of Examples 2 to 4 and ComparativeExample 2 and 3.

FIG. 6 is a van Gurp-Palmen graph of Example 5 and Comparative Examples4 to 7.

FIG. 7 is a van Gurp-Palmen graph of Examples 6 and 7 and ComparativeExamples 9 to 12.

BEST MODE

The present invention will be described with reference to specificembodiments and the accompanying drawings. The embodiments will bedescribed in detail in such a manner that the present invention may becarried out by those of ordinary skill in the art. It should beunderstood that various embodiments of the present invention aredifferent, but need not be mutually exclusive. For example, certainshapes, structures, and features described herein may be implemented inother embodiments without departing from the spirit and scope of thepresent invention in connection with one embodiment.

Therefore, the following detailed description is not to be taken in alimiting sense, and the scope of the present invention is to be limitedonly by the appended claims and the entire scope of equivalents thereof,if properly explained.

Also, it will be understood that although the terms “first”, “second”,etc. may be used herein to describe various components, these componentsshould not be limited by these terms. These components are only used todistinguish one component from another.

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings, so that those of ordinary skillin the art can easily carry out the present invention.

The present invention includes a high-density ethylene-based polymerwhich is polymerized under existence of a hybrid supported metallocenecatalyst.

The polymer is a concept which includes a copolymer.

Hybrid supported metallocene catalysts used herein each independentlyinclude at least one first metallocene compound, at least one secondmetallocene compound, and at least one cocatalyst compound.

The first metallocene compound, which is a transition metal compoundaccording to the present invention, may be represented by Formula 1below.

The first metallocene compound serves to exhibit high activity at thehybrid supported catalyst, and serves to improve a melt flowability of aprepared polymer.

The first metallocene compound has a low mixing rate of comonomer andhas characteristics of forming a low-molecular-weight body, therebyimproving processability in processing the polymer.

In addition, high density is formed due to low mixing of a comonomer,and high activity is exhibited even in high-density production.

Since the first metallocene compound has an asymmetric structure and anon-bridge structure having different ligands, the first metallocenecompound forms a steric hindrance in which a comonomer hardly approachesa catalystic active site. Therefore, the first metallocene serves toreduce the mixing of the comonomer and exhibits both processability andhigh catalystic activity in the preparation of the hybrid supportedmetallocene.

In Formula 1, M1 may be a group 4 transition metal of the periodic tableof the elements, X₁ and X₂ may each independently be a halogen atom, aC₁-C₂₀ alkyl group, a C₂-C₂₀ alkenyl group, a C₂-C₂₀ alkynyl group, aC₆-C₂₀ aryl group, a C₇-C₄₀ alkylaryl group, a C₇-C₄₀ arylalkyl group, aC₁-C₂₀ alkylamido group, a C₆-C₂₀ arylamido group, or a C₁-C₂₀alkylidene group, R₁ to R₁₂ may each independently be a hydrogen atom, asubstituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₂-C₂₀ alkenyl group, a substituted or unsubstituted C₆ toC₂₀ aryl group, a substituted or unsubstituted C₇-C₄₀ alkylaryl group, asubstituted or unsubstituted C₇-C₄₀ arylalkyl group, or a substituted orunsubstituted C₁-C₂₀ silyl group. and may be linked to each other toform a ring, cyclopentadiene linked to R₁ to R₅ and the indene linked toR₆ to R₁₂ are asymmetric structures having different structures, and anon-bridge structure may be formed since the cyclopentadiene and theindene are not linked to each other.

In the present invention, ions or molecules coordinating with thetransition metal (M1 and M2 in Formulae 1 and 2), such ascyclopendadiene linked to R₁ to R₅ and indene linked to R₆ to R₁₂ inFormula 1, and indene linked to R₁₃ to R₁₈ and indene linked to R₂₁ toR₂₆ are referred to as ligands.

In the present invention, the term “substituted” means that a hydrogenatom is substituted with a substituent such as a halogen atom, a C₁-C₂₀hydrocarbon group, a C₁-C₂₀ alkoxy group, and a C₆-C₂₀ aryloxy group,unless otherwise specified.

In addition, the term “hydrocarbon group” means a linear, branched, orcyclic saturated or unsaturated hydrocarbon group, unless otherwisespecified, and the alkyl group, the alkenyl group, the alkynyl group,and the like may be linear, branched, or cyclic.

In a specific example, examples of the transition metal compoundrepresented by Formula 1 include transition metal compounds having thefollowing structures and mixtures thereof, but the present invention isnot limited thereto.

In the transition metal compounds, M is a group 4 transition metal ofthe periodic table of the elements, such as hafnium (Hf), zirconium(Zr), or titanium (Ti), and Me is a methyl group.

The second metallocene compound, which is a transition metal compoundaccording to the present invention, may be represented by Formula 2below.

The second metallocene compound serves to exhibit a high mixing rate ofa comonomer at the hybrid supported catalyst, and serves to improvemechanical properties of the prepared polymer.

The second metallocene compound has a high mixing rate of a comonomerand has characteristics of forming a high-molecular-weight body andconcentrating the distribution of a comonomer on thehigh-molecular-weight body, thereby improving impact strength, flexuralstrength, environmental stress cracking resistance, and melt tension. Inaddition, the second metallocene compound forms a long chain branchedstructure to improve the melt flowability of the high-densitypolyethylene resin having a high molecular weight.

Since the second metallocene compound has a symmetric or asymmetricstructure and a bridge structure having various ligands, the secondmetallocene compound forms a steric hindrance such that the comonomereasily approaches a catalystic active site. Therefore, the secondmetallocene serves to increase the mixing of the comonomer.

In Formula 2, M2 may be a group 4 transition metal of the periodic tableof the elements, X₃ and X₄ may each independently be a halogen atom, aC₁-C₂₀ alkyl group, a C₂-C₂₀ alkenyl group, a C₂-C₂₀ alkynyl group, aC₆-C₂₀ aryl group, a C₇-C₄₀ alkylaryl group, a C₇-C₄₀ arylalkyl group, aC₁-C₂₀ alkylamido group, a C₆-C₂₀ arylamido group, or a C₁-C₂₀alkylidene group, R₁₃ to R₁₈ may each independently be a hydrogen atom,a substituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₂-C₂₀ alkenyl group, a substituted or unsubstitutedC₆-C₂₀ aryl group, a substituted or unsubstituted C₇-C₄₀ alkylarylgroup, a substituted or unsubstituted C₇-C₄₀ arylalkyl group, or asubstituted or unsubstituted C₁-C₂₀ silyl group and may be linked toeach other to form a ring, R₂₁ to R₂₆ may each independently be ahydrogen atom, a substituted or unsubstituted C₁-C₂₀ alkyl group, asubstituted or unsubstituted C₂-C₂₀ alkenyl group, a substituted orunsubstituted C₆-C₂₀ aryl group, a substituted or unsubstituted C₇-C₄₀alkylaryl group, a substituted or unsubstituted C₇-C₄₀ arylalkyl group,or a substituted or unsubstituted C₁-C₂₀ silyl group and may be linkedto each other to form a ring, R₁₉ and R₂₀ may each independently be asubstituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₆-C₂₀ alkenyl group, a substituted or unsubstitutedC₆-C₂₀ aryl group, a substituted or unsubstituted C₇-C₄₀ alkylarylgroup, a substituted or unsubstituted C₇-C₄₀ arylalkyl group, or asubstituted or unsubstituted C₁-C₂₀ silyl group and may be linked toeach other to form a ring, indene linked to R₁₃ to R₁₈ and indene linkedto R₂₁ to R₂₆ may have the same structure or different structures, andindene linked to R₁₃ to R₁₈ and indene linked to R₂₁ to R₂₆ may belinked to Si to form a bridge structure.

In the present invention, the term “substituted” means that a hydrogenatom is substituted with a substituent such as a halogen atom, a C₁-C₂₀hydrocarbon group, a C₁-C₂₀ alkoxy group, and a C₆-C₂₀ aryloxy group,unless otherwise specified. In addition, the term “hydrocarbon group”means a linear, branched, or cyclic saturated or unsaturated hydrocarbongroup, unless otherwise specified, and the alkyl group, the alkenylgroup, the alkynyl group, and the like may be linear, branched, orcyclic.

In a specific example, examples of the transition metal compoundrepresented by Formula 2 include transition metal compounds having thefollowing structures and mixtures thereof, but the present invention isnot limited thereto.

In the transition metal compounds, M is a group 4 transition metal ofthe periodic table of the elements, for example, hafnium (Hf), zirconium(Zr), or titanium (Ti), Me is a methyl group, and Ph is a phenyl group.

The catalyst composition according to the present invention may includea cocatalyst compound containing at least one compound selected from thegroup consisting the compounds represented by Formulae 3 to 6 and thetransition metal compound.

In Formula 3, AL is aluminum, R₂₇ is a halogen atom, a C₁-C₂₀hydrocarbon group, or a C₁-C₂₀ hydrocarbon group substituted withhalogen, and a is an integer of 2 or more.

wherein, in Formula 4, AL is aluminum or boron, R₂₈ is a halogen atom, aC₁-C₂₀ hydrocarbon group, a C₁-C₂₀ hydrocarbon group substituted with ahalogen atom, or a C₁-C₂₀ alkoxy group.

[L1-H]⁺[Z1(A2)₄]⁻  [Formula 5]

[L2]⁺[Z2(A3)₄]⁻  [Formula 6]

In Formulae 5 and 6, L1 and L2 are neutral or cationic Lewis acids, Z1and Z2 are group 13 elements of the periodic table of the elements, andA2 and A3 are a substituted or unsubstituted C₆-C₂₀ aryl group or asubstituted or unsubstituted C₁-C₂₀ alkyl group.

The compound represented by Formula 3 is aluminoxane and is notparticularly limited as long as the compound is generalalkylaluminoxane. For example, methyl aluminoxane, ethyl aluminoxane,isobutyl aluminoxane, butyl aluminoxane, and the like may be used.Specifically, methylaluminoxane may be used. The alkyl aluminoxane maybe prepared by a general method, such as a method of adding anappropriate amount of water to trialkylaluminum or a method of reactingtrialkylaluminum with a hydrocarbon compound or an inorganic hydratesalt including water. Generally, the alkyl aluminoxane is obtained inthe form of a mixture of linear and cyclic aluminoxanes.

As the compound represented by Formula 4, for example, a general alkylmetal compound may be used. Specific examples of the compoundrepresented by Formula 4 include trimethylaluminum, triethylaluminum,triisobutylaluminum, tripropylaluminum, tributylaluminum,dimethylchloroaluminum, triisopropylaluminum, tricyclopentylaluminum,tripentylaluminum, triisopentylaluminum, trihexylaluminum,trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum,triphenylaluminum, tri-p-tolylaluminum, dimethylaluminummethoxide,dimethylaluminumethoxide, trimethylboron, triethylboron,triisobutylboron, tripropyl boron, tributylboron, andtripentafluorophenylboron. More specific examples of the compoundrepresented by Formula 4 include trimethylaluminum, triisobutylaluminum,and tripentafluorophenylboron.

Examples of the compound represented by Formula 5 or 6 includemethyldioctadecylammonium tetrakis(pentafluorophenyl)borate([HNMe(C₁₈H₃₇)₂]+[B(C₆F₅)₄]−), trimethylammonium tetrakis(phenyl)borate,triethylammonium tetrakis(phenyl)borate, tripropylammoniumtetrakis(phenyl)borate, tributylammonium tetrakis(phenyl)borate,trimethylammonium tetrakis(p-tolyl)borate, tripropylammoniumtetrakis(p-tolyl)borate, trimethylammoniumtetrakis(o,p-dimethylphenyl)borate, triethylammoniumtetrakis(o,p-dimethylphenyl)borate, trimethylammoniumtetrakis(p-trifluoromethylphenyl)borate, tributylammoniumtetrakis(p-trifluoromethylphenyl)borate, tributylammoniumtetrakis(pentafluorophenyl)borate, diethylammoniumtetrakis(pentafluorophenyl)borate, triphenylphosphoniumtetrakis(phenyl)borate, trimethylphosphonium tetrakis(phenyl)borate,N,N-diethylanilinium tetrakis(phenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N-diethylaniliniumtetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis(p-trifluoromethylphenyl)borate, triphenylcarbeniumtetrakis(pentafluorophenyl)borate, trimethylammoniumtetrakis(phenyl)aluminate, triethylammonium tetrakis(phenyl)aluminate,tripropylammonium tetrakis(phenyl)aluminate, tributylammoniumtetrakis(phenyl)aluminate, trimethylammonium tetrakis(p-tolyl)aluminate,tripropylammonium tetrakis(p-tolyl)aluminate, triethylammoniumtetrakis(o,p-dimethylphenyl)aluminate, tributylammoniumtetrakis(p-trifluoromethylphenyl)aluminate, trimethylammoniumtetrakis(p-trifluoromethylphenyl)aluminate, tributylammoniumtetrakis(pentafluorophenyl)aluminate, N,N-diethylaniliniumtetrakis(phenyl)aluminate, N,N-diethylaniliniumtetrakis(phenyl)aluminate, N,N-diethylaniliniumtetrakis(pentafluorophenyl)aluminate, diethylammoniumtetrakis(pentafluorophenyl)aluminate, triphenylphosphoniumtetrakis(phenyl)aluminate, trimethylphosphoniumtetrakis(phenyl)aluminate, triethylammonium tetrakis(phenyl)aluminate,and tributylammonium tetrakis(phenyl)aluminate, but the presentinvention is not limited thereto. Specific examples of the compoundrepresented by Formula 5 or 6 include methyldioctadecylammoniumtetrakis(pentafluorophenyl)borate ([HNMe(C₁₈H₃₇)₂]+[B(C₆F₅)₄]−),N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, andtriphenylcarbenium tetrakis(pentafluorophenyl)borate may be used.

In the preparation of the hybrid supported metallocene catalystaccording to the present invention, a mass ratio of the transition metal(M1 of Formula 1 and M2 of Formula 2) to the carrier in the first andsecond metallocene compounds is preferably 1:1 to 1:1,000. The massratio may be preferably 1:100 to 1:500. When the carrier and themetallocene compound are contained at the above-described mass ratio,appropriate supported catalyst activity is exhibited, which isadvantageous in maintaining the activity of the catalyst and achievingcost reduction.

In addition, a mass ratio of the cocatalyst compound represented byFormula 5 or 6 to the carrier is preferably 1:20 to 20:1, and the massratio of the cocatalyst compound represented by Formula 3 or 4 to thecarrier is preferably 1:100 to 100:1.

The mass ratio of the first metallocene compound to the secondmetallocene compound is preferably 1:100 to 100:1. When the cocatalystand the metallocene compound are contained at the above-described massratio, it is advantageous in maintaining the activity of the catalystand achieving cost reduction.

As a carrier suitable for the preparation of the hybrid supportedmetallocene catalyst according to the present invention, a porousmaterial having a large surface area may be used.

The first and second metallocene compounds and the cocatalyst compoundmay be a supported catalyst that is hybrid-supported on the carrier andused as the catalyst. The supported catalyst means a catalyst that iswell dispersed so as to improve catalyst activity and maintain stabilityand is supported on a carrier for stable maintenance.

The hybrid support refers to not supporting the first and secondmetallocene compounds on the carriers but supporting the catalystcompound on the carrier in one step. Due to the reduction in preparingtime and the reduction in amount of a solvent used, the hybrid supportmay be said to be much more cost-effective than individual supports.

The carrier is a solid that disperses and stably retains a materialhaving a catalytic function, and is usually a material having a largeporosity or a large area so as to be highly dispersed and supported soas to increase the exposed surface area of the material having thecatalytic function. The carrier should be stable mechanically,thermally, and chemically. Examples of the carrier include silica,alumina, titanium oxide, zeolite, zinc oxide starch, and syntheticpolymer, but the present invention is not limited thereto.

The carrier may have an average particle size of 10 microns to 250microns, preferably 10 microns to 150 microns, and more preferably 20microns to 100 microns.

The carrier may have a microporous volume of 0.1 cc/g to 10 cc/g,preferably 0.5 cc/g to 5 cc/g, and more preferably 1.0 cc/g to 3.0 cc/g.

In addition, the carrier may have a specific surface area of 1 m²/g to1,000 m²/g, preferably 100 m²/g to 800 m²/g, and more preferably 200m²/g to 600 m²/g.

When the carrier is silica, silica may have a drying temperature of 200°C. to 900° C. The drying temperature may be preferably 300° C. to 800°C., and more preferably 400° C. to 700° C. When the drying temperatureis less than 200° C., too much moisture causes surface moisture to reactwith the cocatalyst. When the drying temperature exceeds 900° C., thestructure of the catalyst collapses. The concentration of the hydroxylgroup in the dried silica may be 0.1 mmol/g to 5 mmol/g, preferably from0.7 mmol/g to 4 mmol/g, and more preferably 1.0 mmol/g to 2 mmol/g. Whenthe concentration of the hydroxyl group is less than 0.5 mmol/g, asupported amount of the cocatalyst is lowered. When the concentration ofthe hydroxyl group exceeds 5 mmol/g, the catalyst component isdeactivated, which is not preferable.

The hybrid supported metallocene catalyst according to the presentinvention may be prepared by activating the metallocene catalyst andsupporting the activated metallocene catalyst on the carrier. In thepreparation of the hybrid supported metallocene, the cocatalyst may befirst supported on the carrier. The activation of the metallocenecatalyst may be independently performed and may vary depending on thesituation. That is, the first metallocene compound and the secondmetallocene compound may be mixed, activated, and then supported on thecarrier. The first metallocene compound and the second metallocenecompound may be supported after the cocatalyst compound is supported onthe carrier.

Examples of the solvent of the reaction in the preparation of the hybridsupported metallocene catalyst include an aliphatic hydrocarbon solventsuch as hexane or pentane, an aromatic hydrocarbon solvent such astoluene or benzene, a hydrocarbon solvent substituted with a chlorineatom such as dichloromethane, an ether-based solvent such as diethylether or tetrahydrofuran, and most organic solvents such as acetone orethyl acetate. Toluene or hexane is preferable, but the presentinvention is not limited thereto.

The reaction temperature in the production of the catalyst is 0° C. to100° C., and preferably 25° C. to 70° C., but the present invention isnot limited thereto.

The reaction time in the preparation of the catalyst is 3 minutes to 48hours, and preferably 5 minutes to 24 hours, but the present inventionis not limited thereto.

The activation of the metallocene compound may be prepared by mixing(contacting) the cocatalyst compound. The mixing may be performed in aninert atmosphere, typically nitrogen or argon, without using a solvent,or in the presence of the hydrocarbon solvent.

The temperature in the activation of the first and second metallocenecompounds may be 0° C. to 100° C., and preferably 10° C. to 30° C.

When the first and second metallocene compounds are activated with thecocatalyst compound, the stirring time may be 5 minutes to 24 hours, andpreferably 30 minutes to 3 hours.

In the metallocene compound, the catalyst composition in a solutionstate, which is uniformly dissolved in the hydrocarbon solvent or thelike, is used as it is. Alternatively, the metallocene compound may beused in a solid powder state in which the solvent is removed by using aprecipitation reaction and vacuum drying is performed at 20° C. to 200°C. for 1 hour to 48 hours. However, the present invention is not limitedthereto.

The method for preparing the high-density ethylene-based polymeraccording to the present invention includes preparing a polyolefinhomopolymer or copolymer by contacting the hybrid supported metallocenecatalyst with at least one olefin monomer.

The method (polymerization reaction) for preparing the high-densitypolyethylene polymer according to the present invention may be a slurryphase polymerization reaction using an autoclave reactor or may be a gasphase polymerization reaction using a gas phase polymerizer. Inaddition, the respective polymerization reaction conditions may bevariously modified according to the desired polymerization result of thepolymerization method (slurry phase polymerization, gas phasepolymerization) or the form of the polymer. The degree of themodification thereof may be easily performed by those of ordinary skillin the art.

When the polymerization is performed in a liquid phase or a slurryphase, a solvent or olefin itself may be used as a medium. Examples ofthe solvent may include propane, butane, pentane, hexane, octane,decane, dodecane, cyclopentane, methylcyclopentane, cyclohexane,methylcyclohexane, benzene, toluene, xylene, dichloromethane,chloroethane, dichloroethane, and chlorobenzene, and these solvents maybe mixed at a predetermined ratio, but the present invention is notlimited thereto.

In a specific example, examples of the olefin monomer may includeethylene, α-olefins, cyclic olefins, dienes, trienes, and styrenes, butthe present invention is not limited thereto.

The α-olefins include a C₃-C₁₂ (for example, C₃-C₈) aliphatic olefin.Specific examples of the α-olefins may include propylene, 1-butene,1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene,3-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene,1-1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-aitosen,4,4-dimethyl-1-pentene, 4,4-diethyl-1-hexene, and 3,4-dimethyl-1-hexene.

The α-olefins may be homopolymerized, or two or more olefins may bealternating, random, or block copolymerized. The copolymerization of theα-olefins may include copolymerization of ethylene and a C₃-C₁₂ (forexample, C₃-C₈) α-olefin (specifically, ethylene and propylene, ethyleneand 1-butene, ethylene and 1-hexene, ethylene and 4-methyl-1-pentene,ethylene and 1-octene, or the like) and copolymerization of propyleneand a C₄-C₁₂ (for example, C₄-C₈) α-olefins (specifically, propylene and1-butene, propylene and 4-methyl-1-pentene, propylene and4-methyl-butene, propylene and 1-hexene, propylene and 1-octene, or thelike). In the copolymerization of ethylene or propylene and anotherα-olefin, the amount of the other α-olefin may be 99 mol % or less ofthe total monomer, and preferably 80 mol % or less in the case of theethylene copolymer.

Preferable examples of the olefin monomer may include ethylene,propylene, 1-butene, 1-hexene, 1-octene, 1-decene, or mixtures thereof,but the present invention is not limited thereto.

In the method for preparing the high-density polyethylene resinaccording to the present invention, the amount of the catalystcomposition used is not particularly limited. For example, in thepolymerization reaction system, the central metal (M, group 4 transitionmetal) represented by Formulae 1 and 2 may have a concentration of1*10⁻⁵ mol/1 to 9*10⁻⁵ mol/1.

In addition, the temperature and pressure at the time of polymerizationmay be changed according to the reactant, the reaction condition, andthe like, and are thus not particularly limited. However, in the case ofthe solution polymerization, the polymerization temperature may be 0° C.to 200° C., and preferably 100° C. to 180° C., and in the case of theslurry phase or gas phase polymerization, the polymerization temperaturemay be 0° C. to 120° C., and preferably 60° C. to 100° C.

In addition, the polymerization pressure may be 1 bar to 150 bar,preferably 30 bar to 90 bar, and more preferably 10 bar to 20 bar. Thepressure may be applied by injecting an olefin monomer gas (for example,ethylene gas).

For example, the polymerization may be performed in a batch (forexample, autoclave reactor), semi-continuous, or continuous (forexample, gas phase polymerization reactor) manner. The polymerizationmay also be performed in two or more steps having different reactionconditions, and the molecular weight of the final polymer may becontrolled by changing the polymerization temperature or injectinghydrogen into a reactor.

The high-density ethylene-based resin according to the present inventionmay be obtained by homopolymerization of ethylene or copolymerization ofethylene and α-olefin using the hybrid supported metallocene compound asa catalyst, and has a unimodal molecular weight distribution.

Hereinafter, the high-density ethylene-based polymer according to thepresent invention will be specifically described.

The high-density ethylene-based polymer according to the presentinvention may have a density of 0.930 g/cm³ to 0.970 g/cm³, and morepreferably 0.950 g/cm³ to 0.965 g/cm³. When the density of the polymeris 0.930 g/cm³ or less, the polymer may not exhibit sufficiently hightoughness. When the density of the polymer is 0.970 g/cm³ or more, it isnot preferable since the degree of crystallization becomes excessivelylarge and brittle fracture easily occurs in a molded body.

Generally, when a melt index (MI) increases, moldability is improved,but impact resistance is deteriorated. For this reason, in the case ofincreasing the MI so as to improve the moldability, a method is usedwhich forms a short chain branched structure (reduction in density)through general copolymerization so as to prevent deterioration ofimpact resistance. However, since the reduction in density of ethyleneleads to deterioration of the toughness of the polymer, there is alimitation in application due to the reduction in density. When the MIis lowered, impact resistance and chemical resistance are improved, butmelt flowability is deteriorated and moldability is significantlydeteriorated. In contrast, the high-density polyethylene polymeraccording to the present invention has a low MI and thus exhibitsexcellent impact resistance and chemical resistance, unlike aconventional high-density polyethylene polymer. In addition, thehigh-density polyethylene polymer according to the present invention hasa wide molecular weight distribution and a long chain branch, and thusexhibits excellent injection moldability.

The melt flowability used herein mainly corresponds to an extrusion loadat the time of extruding a molten resin from an extruder, and MI, MFI,MFR, or the like is used as an index for the standard of the meltflowability. In the present invention, the MI (melt index) indicatesflowability in a load of 2.16 kg at 190° C., and the MFI indicatesflowability in a load of 21.6 kg at 190° C. MFR indicates a ratio of MFIto MI, that is, MFI/MI.

The high-density ethylene-based polymer according to the presentinvention may have an MI of 0.1 g/10 min to 50 g/10 min, and preferably0.5 g/10 min to 10 g/10 min. When the MI is 0.1 g/10 min or less, themolding processability is significantly deteriorated when the polymer isused as an injection molding material, and the appearance of theinjection product is poor. When the MI is greater than 50 g/10 min, theimpact resistance is significantly lowered.

The high-density ethylene-based polymer according to the presentinvention may have an MFR of 35 to 100, and more preferably 37 to 80.When the MFR is 35 or less, molding processability is significantlydeteriorated when the polymer is used as an injection molding material.If the MFR is 100 or more, mechanical properties are deteriorated.

In addition, the y-axis complex viscosity (Poise) graph according to thefrequency (rad/s) of the x-axis in FIGS. 2 to 4 relates to theflowability. The flowability is greater when the complexity viscosity ishigh at a low frequency and the complexity viscosity is low at a highfrequency. This is expressed as a large shear thinning. Theethylene-based polymer according to the present invention exhibitsremarkably excellent melt flowability, as compared with the conventionalhigh-density ethylene-based polymer having similar MI and density.Accordingly, it can be seen that the shear thinning effect is moreexcellent than the high-density ethylene-based polymer having an MIrange of the present invention, preferably, a similar MI in a range of0.5 g/10 min to 10 g/10 min, and shows excellent flowability andprocessability.

In addition, the hybrid supported metallocene catalyst according to thepresent invention can induce the generation of the long chain branch inthe produced high-density ethylene-based polymer. Accordingly, it ispossible to produce the high-density ethylene-based polymer including along chain branch (LCB) having side branches of 6 or more carbon atomsin a main chain.

The presence or absence of the long chain branch in the ethylene-basedpolymer may be determined according to the presence or absence of aninflection point in the van Gurp-Palmen graph measured using a rheometeror the presence or absence of the tendency to diverge as a complexmodulus (G*) becomes smaller.

Referring to the van Gurp-Palmen graphs of FIGS. 5 to 7 of the presentinvention, as the complex modulus value that is the x-axis decreases,the phase angle of the y-axis diverges, and as the complex modulus valueincreases, it has an inflection point. The characteristics of thesegraphs are shown by the long chain branch of the ethylene-based polymer.

In addition, in FIG. 1, the ethylene-based polymer according to thepresent invention exhibits high characteristic relaxation time (k), ascompared with the conventional high-density ethylene-based polymerhaving similar MI and density. The relaxation time (k) means the timefor the stress inside the polymer to return to an equilibrium stateafter a certain strain is applied to the polymer. The relaxation time(k) is related to entanglement of the polymer. When the polymer contentof the ethylene-based polymer is increased or the long chain branch ispresent, entanglement becomes strong. This increases entanglement of thechains and increases the relaxation time. As described above, therelaxation time is related to the long chain branch of the polymer.

In the present invention, the characteristic relaxation time (k)obtained through the cross model is used by using the complex viscositymeasurement value obtained through the rheometer.

The complex viscosity, frequency, and stress relaxation time can beexpressed by the following cross model. ω0, η0, and n are valuesdetermined by curve-fitting the measured melt complex viscosity (η*) inthe frequency (ω) range through the rheometer. Then, the characteristicrelaxation time (λ) takes a reciprocal of ω0 determined by the crossmodel.

$\frac{\eta^{*}}{\eta_{0}} = \frac{1}{\left\lbrack {1 + \left( {\omega/\omega_{0}} \right)^{1 - n}} \right\rbrack}$$\lambda = \frac{1}{\omega_{0}}$

η*: Complex viscosity at a specific frequency in a range of 0.1 rad/s to500 rad/s

η₀: Viscosity when a frequency is closer to 0,

${\lim\limits_{\omega->0}\; {\eta^{*}(\omega)}} = \eta_{0}$

ω: Specific frequency in a range of 0.1 rad/s to 500 rad/s

ω₀: Frequency at point at which shear thinning is started or point atwhich newtonian plateau is ended

λ: Characteristic relaxation time (s)

n: Power-law flow behavior index (0<n<1)

The characteristic relaxation time (λ) in the present invention is 0.3 sto 2.0 s, preferably 0.4 s to 1.9 s, and more preferably 0.5 s to 1.8 s.The ethylene-based polymer according to the present invention exhibitshigh characteristic relaxation time (k), as compared with theconventional high-density ethylene-based polymer having similar MI anddensity. The relationship between the MI and the characteristicrelaxation time (λ) can be expressed by the following relationalexpression.

−0.445 ln(MI)+3.6023>λ>−0.323 ln(MI)+0.696,

preferably −0.441 ln(MI)+2.6004>λ>−0.338 ln(MI)+0.7256, and

more preferably −0.437 ln(MI)+1.5704>λ>−0.383 ln(MI)+0.9163.

Generally, when the MI is low, the mechanical properties may beimproved, but the melt flowability is deteriorated and theprocessability is deteriorated. However, it is confirmed that thehigh-density polyethylene resin according to the present invention has alow MI and thus has excellent mechanical properties, and includes a longchain branch and thus exhibits a high MFR, thereby providing excellentprocessability.

The high-density polyethylene resin according to the present inventionhas a low MI, but exhibits more excellent processability than theconventional HDPE due to high MFR characteristics.

The high-density ethylene-based polymer according to the presentinvention can be used as a material for injection molding, compressionmolding, or rotational molding.

EXAMPLES

Hereinafter, the structure and operation of the present invention willbe described in more detail with reference to preferred examples of thepresent invention. However, these example are shown by way ofillustration and should not be construed as limiting the presentinvention in any way.

Since contents not described here can be sufficiently technicallyinferred by those of ordinary skill in the art, descriptions thereofwill be omitted.

Preparation Example 1 of First Metallocene Compound.[Indenyl(cyclopentadienyl)]ZrCl₂

Indene (5 g, 0.043 mol) was dissolved in hexane (150 ml). The mixturewas sufficiently mixed and cooled to a temperature of −30° C. 2.5Mn-butyllithium (n-BuLi) hexane solution (17 ml, 0.043 mol) was slowlydropped thereto and stirred at room temperature for 12 hours. A whitesuspension was filtered through a glass filter, and a white solid wassufficiently dried to obtain an indene lithium salt (yield: 99%).

In a slurry solution of the indene lithium salt (1.05 g, 8.53 mmol),CpZrCl₃ (2.24 g, 8.53 mmol) was slowly dissolved in ether (30 mL) andthen cooled to a temperature of −30° C. An indene lithium salt dissolvedin ether (15 mL) was slowly dropped to the ether solution and stirredfor 24 hours to obtain [indenyl(cyclopentadienyl)]ZrCl₂ (yield: 97%).Here, Cp indicates cyclopentadienyl.

Preparation Example 2 of First Metallocene Compound. [2-methylbenzeindenyl (cyclopentadienyl)]ZrCl₂

[2-methyl benzeindenyl (cyclopentadienyl)]ZrCl₂ (yield: 95%) wasobtained in the same manner as in Preparation Example 1 by using2-methylbenzeindene.

Preparation Example 3 of First Metallocene Compound. [2-phenylbenzeindenyl (tetramethylcyclopentadienyl)]ZrCl₂

[2-phenyl benzeindenyl (tetramethylcyclopentadienyl)]ZrCl₂ (yield: 93%)was obtained in the same manner as in Preparation Example 1 by using2-methylbenzeindene and tetrametylcyclopentadiene.

Preparation Example 4 of First Metallocene Compound.[fluorenyl(cyclopentadienyl)]ZrCl₂

[2-phenyl benzeindenyl (tetramethylcyclopentadienyl)]ZrCl₂ (yield: 92%)was obtained in the same manner as in Preparation Example 1 by usingfluorene and cyclopentadiene.

Preparation Example 5 of Second Metallocene Compound.Me₂Si{2-methyl-4-(1-naphthyl)}₂ZrCl₂

Preparation Example 5-1: Preparation of Ligand Compound

2-methyl-4-bromo indene (2 g, 1 eq), Pd(PPh₃)₄ (553 mg, 0.05 eq), and1-NaphB(OH)₂ (2.14 g, 1.3 eq) were added to a solution of THF and MeOH(4:1, 40 ml), and degassed K₂CO₃ aqueous solution (2.0 M, 3.3 eq) wasadded thereto at room temperature. The mixture was stirred under refluxat a temperature of 80° C. for 12 hours to obtain2-methyl-4-(1-naphthyl)indene. 2-methyl-4-(1-naphthyl)indene was addedto 50 mL of toluene, and n-BuLi (7.8 mL, 1.1 eq, 1.6 M in hexane) wasslowly added thereto at a temperature of −30° C. The mixture wasgradually heated to room temperature and stirred for 12 hours. A solidgenerated therefrom was filtered, washed with hexane, and dried undervacuum to obtain 2-methyl-4-(1-naphthyl)indenyl lithium.

SiMe₂Cl₂ (462 mg, 1 eq) was slowly added to2-methyl-4-(1-naphthyl)indenyl lithium (1.88 g, 2 eq), 13 mL of toluene,and 3 mL of THF at a temperature of −30° C., and the mixture wasgradually heated and stirred at a temperature of 55° C. for 12 hours toobtain 1.97 g (97%) ofdimethylbis{2-methyl-4-(1-naphthyl)indenyl)}silane.

Preparation Example 5-2: Preparation of Second Metallocene Compound

The compound (0.4 g, 1 eq) prepared in Preparation Example 5-1 was addedto 15 mL of tetrahydrofuran (THF), and n-BuLi (1.32 mL, 2.2 eq, 1.6 M inhexane) was slowly added thereto at a temperature of −30° C. The mixturewas gradually heated to room temperature and stirred for 12 hours toobtain dilithium salt. ZrCl₄ (435 mg, 1 eq) was slowly added to adilithium salt slurry solution and stirred for 12 hours. A solvent wasremoved therefrom under vacuum, and a product obtained therefrom waswashed with THF and MC to obtain Me₂Si{2-methyl-4-(1-naphthyl)}2ZrCl₂(yield: 94%).

Preparation Example 6 of Second Metallocene Compound.Me₂Si{2-methyl-4-(2-naphthyl)}2ZrCl₂ Preparation Example 6-1:Preparation of Ligand Compound

Dimethylbis{2-methyl-4-(2-naphthyl) indenyl)}silane (yield: 51%) wasobtained in the same manner as in Preparation Example 5-1 by using2-methyl-7-(2-naphthyl)indene.

Preparation Example 6-2: Preparation of Second Metallocene Compound

Me₂Si{2-methyl-4-(2-naphthyl)}₂ZrCl₂ (yield: 90%) was obtained in thesame manner as in Preparation Example 5-2 by using the compound preparedin Preparation Example 6-1.

Preparation Example 7 of Second Metallocene Compound.(Me₂Si(2-methyl-4-phenyl indenyl)₂ZrCl₂) Preparation Example 7-1:Preparation of Ligand Compound

2-methyl-4-bromo indene (2 g, 1 eq) (7 g, 1 eq) and Ni(dppp)Cl₂ (363 mg,0.02 eq) were added to ether (100 mL), and PhMgBr (3.0 M in ether, 13.3g, 1.05 eq) was added thereto at a temperature of 0° C. for 1 hour. Themixture was gradually heated to room temperature (25° C.) and stirredunder reflux at a temperature of 50° C. for 12 hours. After the reactionwas completed, the solution was immersed in an ice bath, and 1N HCl wasadded thereto to lower pH to 4. An organic layer was extracted therefromwith a separatory funnel and treated with MgSO₄ to remove watertherefrom. The organic layer was filtered and a solvent was dried toobtain 2-methyl-4-(phenyl)indene (yield: 97%). Me₂Si(2-methyl-4-phenylindenyl)₂ (yield: 95%) was prepared in the same manner as in PreparationExample 5-by using 2-methyl-4-(phenyl)indene. Here, dppp indicates1,3-bis(diphenylphosphino)propane.

Preparation Example 7-2: Preparation of Second Metallocene Compound

Me₂Si(2-methyl-4-phenyl indenyl)₂ZrCl₂ (yield: 90%) was obtained in thesame manner as in Preparation Example 5-2 by usingMe₂Si(2-methyl-4-phenylindene)₂.

Preparation Example 8 of Hybrid Supported Metallocene Catalyst

The first and second metallocene compounds and methylaluminoxane (MAO)as the cocatalyst lost activity when reacted with moisture or oxygen inthe air. Therefore, all experiments were performed under a nitrogencondition by using a glove box and a Schlenk technique. A 10 L supportedcatalyst reactor was washed to remove foreign matter therefrom. The 10 Lsupported catalyst reactor was closed while drying at a temperature of110° C. for 3 hours or more, and was then in a state in which moistureor the like was completely removed using a vacuum.

10 wt % of methylalumoxane (MAO) solution (methylaluminoxane: 1,188 g)was added to 2.862 g of the compound prepared in Preparation Example 1and 3.469 g of the compound 7-2 prepared in Preparation Example 8-2, andthe mixture was stirred at room temperature for 1 hour. After 300 g ofsilica (XPO2402) was added to the reactor, 900 mL of purified toluenewas added to the reactor and then stirred. After the stirring step for 1hour was completed, a first metallocene compound, a second metallocenecompound, and a methylaluminoxane mixed solution were added to thereactor while stirring the reactor. The reactor was heated to atemperature of 60° C. and stirred for 2 hours.

After a precipitation reaction, a supernatant was removed, washed with 1L of toluene, and vacuum-dried at a temperature of 60° C. for 12 hours.

Preparation Example 9 of Hybrid Supported Metallocene Catalyst

A hybrid supported metallocene catalyst was prepared in the same manneras in Preparation Example 8, except that 2.389 g of the compoundprepared in Preparation Example 2 and 4.387 g of the compound preparedin Preparation Example 7-2 were used.

Preparation Example 10 of Hybrid Supported Metallocene Catalyst

A hybrid supported metallocene catalyst was prepared in the same manneras in Preparation Example 8, except that 2.712 g of the compoundprepared in Preparation Example 3 and 3.046 g of the compound preparedin Preparation Example 6-2 were used.

Preparation Example 11 of Hybrid Supported Metallocene Catalyst

A hybrid supported metallocene catalyst was prepared in the same manneras in Preparation Example 8, except that 2.662 g of the compoundprepared in Preparation Example 4 and 3.712 g of the compound preparedin Preparation Example 5-2 were used.

Example 1

An olefin polymer was prepared by adding the hybrid supportedmetallocene catalyst obtained in Preparation Example 8 to a continuouspolymerization reactor for a fluidized bed gas process. 1-hexene wasused as a comonomer, a reactor ethylene pressure was maintained at 15bar, and a polymerization temperature was maintained at 80° C. to 90° C.

Examples 2 to 8

Olefin polymers were prepared in the same manner as in Example 1, exceptthat the hybrid supported metallocene catalysts prepared in PreparationExamples 9 to 11 were used.

Comparative Example 1

A commercial product HDPE 7303 (manufactured by SK Global Chemical Co.,Ltd.) was used.

Comparative Example 1 had a density of 0.9523 g/cm³ according to ASTMD1505 and a melt index (MI) of 2.1 g/10 min according to ASTM D1238.

Comparative Example 2

A commercial product HDPE ME2500 (manufactured by LG Chemical Co., Ltd.)was used.

Comparative Example 2 had a density of 0.9538 g/cm³ according to ASTMD1505 and a melt index (MI) of 2.1 g/10 min according to ASTM D1238.

Comparative Example 3

A commercial product HDPE C910A (manufactured by Hanwha TotalPetrochemical Co., Ltd.) was used.

Comparative Example 3 had a density of 0.9556 g/cm³ according to ASTMD1505 and a melt index (MI) of 2.4 g/10 min according to ASTM D1238.

Comparative Example 4

A commercial product HDPE 7390 (manufactured by Hanwha ChemicalCorporation) was used.

Comparative Example 4 had a density of 0.9532 g/cm³ according to ASTMD1505 and a melt index (MI) of 4.2 g/10 min according to ASTM D1238.

Comparative Example 5

A commercial product HDPE M850 (manufactured by Korea Petrochemical Ind.Co., Ltd.) was used.

Comparative Example 5 had a density of 0.9642 g/cm³ according to ASTMD1505 and a melt index (MI) of 4.9 g/10 min according to ASTM D1238.

Comparative Example 6

A commercial product HDPE 2200J (manufactured by Lotte ChemicalCorporation) was used.

Comparative Example 6 had a density of 0.9582 g/cm³ according to ASTMD1505 and a melt index (MI) of 5.1 g/10 min according to ASTM D1238.

Comparative Example 7

A commercial product ME6000 (manufactured by LG Chemical Co., Ltd.) wasused.

Comparative Example 7 had a density of 0.9621 g/cm³ according to ASTMD1505 and a melt index (MI) of 5.8 g/10 min according to ASTM D1238.

Comparative Example 8

A commercial product HDPE 7210 (manufactured by SK Global Chemical Co.,Ltd.) was used.

Comparative Example 8 had a density of 0.9579 g/cm³ according to ASTMD1505 and a melt index (MI) of 6.1 g/10 min according to ASTM D1238.

Comparative Example 9

A commercial product HDPE M680 (manufactured by Korea Petrochemical Ind.Co., Ltd.) was used.

Comparative Example 9 had a density of 0.9562 g/cm³ according to ASTMD1505 and a melt index (MI) of 6.9 g/10 min according to ASTM D1238.

Comparative Example 10

A commercial product HDPE 7600 (manufactured by Hanwha ChemicalCorporation) was used.

Comparative Example 10 had a density of 0.9592 g/cm³ according to ASTMD1505 and a melt index (MI) of 7.2 g/10 min according to ASTM D1238.

Comparative Example 11

A commercial product HDPE 2210J (manufactured by Lotte ChemicalCorporation) was used.

Comparative Example 11 had a density of 0.9580 g/cm³ according to ASTMD1505 and a melt index (MI) of 8.0 g/10 min according to ASTM D1238.

Comparative Example 12

A commercial product ME8000 (manufactured by LG Chemical Co., Ltd.) wasused.

Comparative Example 12 had a density of 0.9592 g/cm³ according to ASTMD1505 and a melt index (MI) of 8.0 g/10 min according to ASTM D1238.

<Physical Property Measurement Method>

1) A density was measured according to ASTM 1505.

2) MI, MFI, and MFR

Melt flowability MI was an amount of extrusion for 10 minutes at a loadof 2.16 kg, and was measured at a measurement temperature of 190° C.according to ASTM 1238.

MFI was an amount of extrusion for 10 minutes at a load of 21.6 kg, andwas measured at a measurement temperature of 190° C. according to ASTM1238.

MFR indicates a ratio of MFI to MI, that is, MFI/MI.

3) The complex viscosity for the frequency was measured by TA's ARESrheometer. After a preheating time of 30 seconds at a measurementtemperature of 190° C., the measurement was made at a frequency of 0.1rad/s to 500 rad/s.

4) The characteristic relaxation time (λ) used a value obtained bycurve-fitting the value of the complex viscosity for the frequencythrough the cross model.

The ASTM is the name of the standard and is divided into 1) definitionof common terms in the field, 2) sequence that is considered to beappropriate so as to achieve a given task, 3) method for making a givenmeasurement, 4) criteria for dividing objects or concepts into groups,and 5) determining the range or limitation of characteristics of aproduct or material.

In addition, the MI, i.e., melt index, is a term indicating meltflowability of a plastic material having a predetermined load at apredetermined temperature. As the melt index is higher, theprocessability of the polymer is more excellent. The melt index isinversely proportional to the molecular weight. A polyolefin resin maybe prepared by various molding methods, but these methods are common inthat the resin is first heated to a molten state and then molded.Therefore, the melting property is an extremely important property inthe molding of the polyolefin-based resin. In particular, in the moldingsuch as extrusion molding, compression molding, injection molding, orrotational molding, the melting property, that is, the melt flowability,is an essential property that affects satisfactory moldability. As themelt flow index is larger, the flow becomes easier.

In the present invention, the MI indicates flowability in a load of 2.16kg at 190° C., and the MFI indicates flowability in a load of 21.6 kg at190° C. MFR indicates a ratio of MFI to MI, that is, MFI/MI.

The characteristic relaxation time (λ) is the same as described above.

Table 1 shows the polymerization conditions of Examples 1 to 8.

TABLE 1 Ethylene Hydrogen/ 1-Hexene/ Catalyst pressure Ethylene EthyleneActivity (bar) mole ratio (%) mole ratio (%) (gPE/gCat) Example 1 15.00.084 0.128 4800 Example 2 14.4 0.101 0.161 4900 Example 3 14.7 0.0820.131 4800 Example 4 15.0 0.125 0.157 5100 Example 5 14.6 0.116 0.1414900 Example 6 15.2 0.137 0.154 5000 Example 7 14.9 0.136 0.147 5100Example 8 14.8 0.152 0.152 5200

Table 2 below shows the above-described physical property measurementdata. When compared with twelve commercially available HDPEs, it isconfirmed that the high-density polyethylene copolymer according to thepresent invention has excellent melt flowability.

TABLE 2 Density MI Characteristic (g/cm³) (g/10 min) MFR relaxationtime(s) Example 1 0.9542 1.1 56.1 1.530 Example 2 0.9582 1.6 46.9 0.902Example 3 0.9572 2.5 43.6 1.168 Example 4 0.9563 2.6 42.7 0.751 Example5 0.9567 3.1 44.4 0.803 Example 6 0.9562 6.3 40.5 0.532 Example 7 0.95346.9 39.7 0.508 Example 8 0.9560 8.5 37.0 0.636 Comparative 0.9523 2.137.4 0.267 Example 1 Comparative 0.9538 2.1 28.5 0.088 Example 2Comparative 0.9556 2.4 28.5 0.058 Example 3 Comparative 0.9532 4.2 26.10.026 Example 4 Comparative 0.9642 4.9 34.9 0.116 Example 5 Comparative0.9582 5.1 32.6 0.101 Example 6 Comparative 0.9621 5.8 30.1 0.041Example 7 Comparative 0.9579 6.1 35.4 0.113 Example 8 Comparative 0.95626.9 30.4 0.045 Example 9 Comparative 0.9592 7.2 27.8 0.06 Example 10Comparative 0.9580 8.0 27.6 0.021 Example 11 Comparative 0.9592 8.0 28.50.026 Example 12

In the production of the hybrid supported metallocene, in the asymmetricstructure of the first metallocene of Formula 1 according to the presentinvention, an electron donating phenomenon in which electrons aredonated to a central metal in a ligand is not the same. Thus, since bondlengths between the central metal and the ligand are different from eachother, a steric hindrance when a monomer approaches a catalystic activesite is low.

Since the second metallocene of Formula 2 has a bridge structure form,the second metallocene protects the catalystic active site andfacilitates accessibility of the comonomer to the catalytic active site,thereby providing characteristics in which penetration of comonomer isexcellent. In addition, as compared with the non-bridge structure inwhich the ligands are not linked to each other, the catalytic activesite is stabilized to form a high molecular weight.

However, in the case of the metallocene of Formula 2 alone, activity isexcessively low and is thus cost-ineffective, and ahigh-molecular-weight body is excessively formed and thus processabilityis deteriorated.

The high-density polyethylene resin prepared by using the hybridsupported metallocene catalyst according to the present inventionexhibits shear thinning having a large slope and thus have excellentprocessability.

It can be seen from Table 2 that the metallocene catalyst in which thefirst metallocene of Formula 1 and the second metallocene of Formula 2are hybrid-supported exhibits a high MFR and thus exhibits excellentinjection processability.

Generally, when the MI is low, the mechanical properties may beimproved, but the melt flowability is deteriorated and theprocessability is deteriorated. However, the high-density polyethyleneresin according to the present invention has a low MI and thus exhibitsexcellent mechanical properties.

In addition, it can be seen that the ethylene-based polymer according tothe examples includes the long chain branch from FIGS. 5 to 7 showingthe van Gurp-Palmen graphs and the characteristic relaxation time (k).

In addition, it can be seen in each example that the characteristicrelaxation time is high due to the inclusion of the long chain branch.As described above, since the polymer having a high characteristicrelaxation time has excellent workability, the present invention canconfirm that the processability is excellent because the characteristicrelaxation time obtained by curve-fitting the value of the complexviscosity through the cross model is relatively high.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, the present inventionis not limited to the specific exemplary embodiments. It will beunderstood by those of ordinary skill in the art that variousmodifications may be made thereto without departing from the spirit andscope of the present invention as defined by the appended claims, andsuch modifications fall within the scope of the claims.

1. A high-density ethylene-based polymer prepared by polymerizingethylene and at least one monomer selected from the group consisting ofα-olefin-based monomers, wherein a density is 0.930 g/cm³ to 0.970g/cm³, an MI is 0.1 g/10 min to 50 g/10 min, an MFR is 35 to 100, and acharacteristic relaxation time (λ) is 0.3 s to 2.0 s at 190° C.
 2. Thehigh-density ethylene-based polymer according to claim 1, wherein arelationship between the MI and the characteristic relaxation time (λ)is expressed by Equation 1:−0.445In(MI)+3.6.23>λ,>−0.323In(MI)+0.696.  [Equation 1]
 3. Thehigh-density ethylene-based polymer according to claim 1, wherein thepolymer includes a long chain branch (LCB).
 4. The high-densityethylene-based polymer according to claim 1, wherein the α-olefin-basedmonomer comprises at least one selected from the group consisting ofpropylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene,1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene,and 1-aitosen.
 5. The high-density ethylene-based polymer according toclaim 1, wherein, when the high-density ethylene-based polymer is acopolymer of the ethylene and the α-olefin-based monomer, a content ofthe α-olefin monomer is 0.1 wt % to 10 wt %.
 6. The high-densityethylene-based polymer according to claim 1, wherein the ethylene-basedpolymer is a material for injection molding, compression molding, orrotational molding.
 7. The high-density ethylene-based polymer accordingto claim 1, wherein the high-density ethylene-based polymer ispolymerized by using a catalyst comprising at least one firstmetallocene compound represented by Formula 1, at least one secondmetallocene compound represented by Formula 2, at least one cocatalystcompound, and a carrier:

wherein, in Formula 1, M1 is a group 4 transition metal of the periodictable of the elements, X₁ and X₂ are each independently a halogen atom,a C₁-C₂₀ alkyl group, a C₂-C₂₀ alkenyl group, a C₂-C₂₀ alkynyl group, aC₆-C₂₀ aryl group, a C₇-C₄₀ alkylaryl group, a C₇-C₄₀ arylalkyl group, aC₁-C₂₀ alkylamido group, a C₆-C₂₀ arylamido group, or a C₁-C₂₀alkylidene group, R₁ to R₁₂ are each independently a hydrogen atom, asubstituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₂-C₂₀ alkenyl group, a substituted or unsubstitutedC₆-C₂₀ aryl group, a substituted or unsubstituted C₇-C₄₀ alkylarylgroup, a substituted or unsubstituted C₇-C₄₀ arylalkyl group, or asubstituted or unsubstituted C₁-C₂₀ silyl group and are linked to eachother to form a ring, cyclopentadiene linked to R₁ to R₅ and indenelinked to R₆ to R₁₂ have an asymmetric structure having differentstructures, and the cyclopentadiene and the indene are not linked toeach other to form a non-bridge structure:

wherein, in Formula 2, M2 is a group 4 transition metal of the periodictable of the elements, X₃ and X₄ are each independently a halogen atom,a C₁-C₂₀ alkyl group, a C₂-C₂₀ alkenyl group, a C₂-C₂₀ alkynyl group, aC₆-C₂₀ aryl group, a C₇-C₄₀ alkylaryl group, a C₇-C₄₀ arylalkyl group, aC₁-C₂₀ alkylamido group, a C₆-C₂₀ arylamido group, or a C₁-C₂₀alkylidene group, R₁₃ to R₁₈ are each independently a hydrogen atom, asubstituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₂-C₂₀ alkenyl group, a substituted or unsubstitutedC₆-C₂₀ aryl group, a substituted or unsubstituted C₇-C₄₀ alkylarylgroup, a substituted or unsubstituted C₇-C₄₀ arylalkyl group, or asubstituted or unsubstituted C₁-C₂₀ silyl group and are linked to eachother to form a ring, R₂₁ to R₂₆ are each independently a hydrogen atom,a substituted or unsubstituted C₁-C₂₀ alkyl group, a substituted orunsubstituted C₂-C₂₀ alkenyl group, a substituted or unsubstitutedC₆-C₂₀ aryl group, a substituted or unsubstituted C₇-C₄₀ alkylarylgroup, a substituted or unsubstituted C₇-C₄₀ arylalkyl group, or asubstituted or unsubstituted C₁-C₂₀ silyl group and are linked to eachother to form a ring, R₁₉ and R₂₀ are each independently a substitutedor unsubstituted C₁-C₂₀ alkyl group, a substituted or unsubstitutedC₂-C₂₀ alkenyl group, a substituted or unsubstituted C₆-C₂₀ aryl group,a substituted or unsubstituted C₇-C₄₀ alkylaryl group, a substituted orunsubstituted C₇-C₄₀ arylalkyl group, or a substituted or unsubstitutedC₁-C₂₀ silyl group and are linked to each other to form a ring, indenelinked to R₁₃ to R₁₈ and indene linked to R₂₁ to R₂₆ have the samestructure or different structures, and the indene linked to R₁₃ to R₁₈and the indene linked to R₂₁ to R₂₆ are linked to Si to form a bridgestructure.
 8. The high-density ethylene-based polymer according to claim7, wherein the first metallocene compound comprises at least onecompound selected from the group consisting of compounds having thefollowing structures:


9. The high-density ethylene-based polymer according to claim 7, whereinthe second metallocene compound comprises at least one compound selectedfrom the group consisting of compounds having the following structures:


10. The high-density ethylene-based polymer according to claim 7,wherein the cocatalyst compound comprises compounds represented byFormulae 3 to 6:

wherein, in Formula 3, AL is aluminum, R₂₇ is a halogen atom, a C₁-C₂₀hydrocarbon group, or a C₁-C₂₀ hydrocarbon group substituted withhalogen, and a is an integer of 2 or more:

wherein, in Formula 4, Al is aluminum or boron, and R₂₈ is a halogenatom, a C₁-C₂₀ hydrocarbon group, a C₁-C₂₀ hydrocarbon group substitutedwith halogen, or a C₁-C₂₀ alkoxy:[L1-H]⁺[Z1(A2)₄]⁻  [Formula 5][L2]⁺[Z2(A3)₄]⁻  [Formula 6] wherein, in Formulae 5 and 6, L1 and L2 areneutral or cationic Lewis acids, Z1 and Z2 are group 13 elements of theperiodic table of the elements, and A2 and A3 are a substituted orunsubstituted C₆-C₂₀ aryl group or a substituted or unsubstituted C₁-C₂₀alkyl group.
 11. The high-density ethylene-based polymer according toclaim 10, wherein the cocatalyst compound represented by Formula 3comprises at least one selected from the group consisting ofmethylaluminoxane, ethylaluminoxane, isobutylaluminoxane, andbutylaluminoxane.
 12. The high-density ethylene-based polymer accordingto claim 10, wherein the cocatalyst compound represented by Formula 4comprises at least one compound selected from the group consisting oftrimethylaluminum, triethylaluminum, triisobutylaluminum,tripropylaluminum, tributylaluminum, dimethylchloroaluminum,triisopropylaluminum, tricyclopentylaluminum, tripentylaluminum,triisopentylaluminum, trihexylaluminum, trioctylaluminum,ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum,tri-p-tolylaluminum, dimethylaluminummethoxide,dimethylaluminumethoxide, trimethylboron, triethylboron,triisobutylboron, tripropylboron, tributylboron, andtripentafluorophenylboron.
 13. The high-density ethylene-based polymeraccording to claim 10, wherein the cocatalyst compound represented byFormula 5 or 6 each independently comprises at least one selected fromthe group consisting of methyldioctadecylammoniumtetrakis(pentafluorophenyl)borate, trimethylammoniumtetrakis(phenyl)borate, triethylammonium tetrakis(phenyl)borate,tripropylammonium tetrakis(phenyl)borate, tributylammoniumtetrakis(phenyl)borate, trimethylammonium tetrakis(p-tolyl)borate,tripropylammonium tetrakis(p-tolyl)borate, trimethylammoniumtetrakis(o,p-dimethylphenyl)borate, triethylammoniumtetrakis(o,p-dimethylphenyl)borate, trimethylammoniumtetrakis(p-trifluoromethylphenyl)borate, tributylammoniumtetrakis(p-trifluoromethylphenyl)borate, tributylammoniumtetrakis(pentafluorophenyl)borate, diethylammoniumtetrakis(pentafluorophenyl)borate, triphenylphosphoniumtetrakis(phenyl)borate, trimethylphosphonium tetrakis(phenyl)borate,N,N-diethylanilinium tetrakis(phenyl)borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, N,N-diethylaniliniumtetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis(p-trifluoromethylphenyl)borate, triphenylcarbeniumtetrakis(pentafluorophenyl)borate, trimethylammoniumtetrakis(phenyl)aluminate, triethylammonium tetrakis(phenyl)aluminate,tripropylammonium tetrakis(phenyl)aluminate, tributylammoniumtetrakis(phenyl)aluminate, trimethylammonium tetrakis(p-tolyl)aluminate,tripropylammonium tetrakis(p-tolyl)aluminate, triethylammoniumtetrakis(o,p-dimethylphenyl)aluminate, tributylammoniumtetrakis(p-trifluoromethylphenyl)aluminate, trimethylammoniumtetrakis(p-trifluoromethylphenyl)aluminate, tributylammoniumtetrakis(pentafluorophenyl)aluminate, N,N-diethylaniliniumtetrakis(phenyl)aluminate, N,N-diethylaniliniumtetrakis(phenyl)aluminate, N,N-diethylaniliniumtetrakis(pentafluorophenyl)aluminate, diethylammoniumtetrakis(pentafluorophenyl)aluminate, triphenylphosphoniumtetrakis(phenyl)aluminate, trimethylphosphoniumtetrakis(phenyl)aluminate, triethylammonium tetrakis(phenyl)aluminate,and tributylammonium tetrakis(phenyl)aluminate.
 14. The high-densityethylene-based polymer according to claim 7, wherein a ratio of a totalmass of a transition metal of the first metallocene compound and atransition metal of the second metallocene compound to a mass of thecarrier is 1:1 to 1:1,000, and a mass ratio of the first metallocenecompound to the second metallocene compound is 1:100 to 100:1.
 15. Thehigh-density ethylene-based polymer according to claim 10, wherein amass ratio of the cocatalyst compound represented by Formulae 3 and 4 tothe carrier is 1:100 to 100:1, and a mass ratio of the cocatalystcompound represented by Formulae 5 and 6 to the carrier is 1:20 to 20:1,and
 16. The high-density ethylene-based polymer according to claim 7,wherein the carrier comprises at least one selected from the groupconsisting of silica, alumina, titanium oxide, zeolite, zinc oxide, andstarch, the carrier has an average particle size of 10 microns to 250microns, the carrier has a microporous volume of 0.1 cc/g to 10 cc/g,and the carrier has a specific surface area of 1 m²/g to 1,000 m²/g. 17.A method for preparing a high-density ethylene-based polymer, furthercomprising adding the hybrid supported catalyst according claim 7, atleast one α-olefin monomer selected from the group consisting ofα-olefins, and ethylene to an autoclave reactor or a gas phasepolymerization reactor, and polymerizing a high-density ethylene-basedpolymer in an environment in which a temperature is 0° C. to 120° C. anda pressure is 1 bar to 150 bar.
 18. The high-density ethylene-basedpolymer according to claim 17, wherein the α-olefin monomer comprises atleast one selected from the group consisting of propylene, 1-butene,1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene,1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-aitosen.